"Unit" positioning, "Ten" positioning and exchange method in positioning methods. For example, 1, 2,3 form a two-digit number, and the ten digits and the single digits of each two-digit number cannot be the same.

The "unit" positioning method is to locate 1:2 1, 31in the unit; Position 2 in the unit:12,32; At the position of the unit 3:13,23.

Multiplication:

(1) How much is a few.

(2) How many times is a number?

③ Find the area and volume of the object.

(4) Find the fraction or percentage of a number.

Department:

① Divide a number into several parts on average and find out one of them.

② Find out how many other numbers are in a number.

(3) Given a fraction or percentage of a number, find this number.

(4) Find a number that is several times that of another number.